/*********************************************************************************
 *      Copyright:  (C) 2025 LingYun<iot25@lingyun>
 *                  All rights reserved.
 *
 *       Filename:  select.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(10/03/25)
 *         Author:  LingYun <iot25@lingyun>
 *      ChangeLog:  1, Release initial version on "10/03/25 20:05:41"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <ctype.h>
#include <time.h>
#include <pthread.h>
#include <getopt.h>
#include <libgen.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#define ARRAY_SIZE(x)		(sizeof(x)/sizeof(x[0]))

static inline void msleep(unsigned long ms);
static inline void print_usage(char *progname);
int socket_server_init(char *listen_ip,int listen_port);

int main(int argc, char **argv)
{
	int					listenfd, connfd;
	int					serv_port = 0;
	int					daemon_run = 0;
	char				*progname = NULL;
	int					opt;
	fd_set				rdset;
	int					rv;
	int					i, j;
	int					found;
	int					maxfd = 0;
	char				buf[1024];
	int					fds_array[1024];

	struct option		long_options[]=
	{
		{"daemon", no_argument, NULL, 'b'},
		{"port",required_argument, NULL, 'p'},
		{"help",no_argument, NULL, 'h'},
		{NULL,0, NULL, 0},
	
	};

	progname = basename(argv[0]);

	while((opt = getopt_long(argc, argv, "bp:h", long_options, NULL)) != -1)
	{
		switch(opt)
		{
			case 'b':
				daemon_run =1;
				break;
			case 'p':
				serv_port = atoi(optarg);
				break;
			case 'h':
				print_usage(progname);
				return EXIT_SUCCESS;
			default:
				break;
		}

	}

	if( !serv_port)
	{
		print_usage(progname);
		return -1;

	}

	if((listenfd = socket_server_init(NULL, serv_port)) < 0)
	{
		printf("ERROR: %s server listen on port %d failure\n", argv[0],serv_port);
		return -2;
	}
	printf("%s server start to listen on port %d \n",argv[0],serv_port);

/*set progname runing on background */
	if( daemon_run )
	{
		daemon(0,0);
	}

	for(i=0; i<ARRAY_SIZE(fds_array); i++)
	{
		fds_array[i]= -1;
	}
	fds_array[0] = listenfd;

	for( ; ; )
	{
		FD_ZERO(&rdset);
		for(i=0; i<ARRAY_SIZE(fds_array); i++)
		{
			if(fds_array[i] < 0)
				continue;

			maxfd = fds_array[i]>maxfd?fds_array[i]:maxfd;
			FD_SET(fds_array[i],&rdset);

		}
/* program will be blocked here */
		rv = select(maxfd+1, &rdset, NULL, NULL,NULL);
		if(rv<0)
		{
			printf("select failure: %s\n",strerror(errno));
			break;
		}
		else if(rv==0)
		{
			printf("select get timeout\n");
			continue;
		}

		/* listen socket get event means new client start connect now */
		if( FD_ISSET(listenfd, &rdset))
		{
			if((connfd=accept(listenfd, (struct sockaddr *)NULL, NULL))<0)
			{
				printf("accept new client failure: %s\n",strerror(errno));
				continue;
			}

			found = 0;
			for(i=0; i<ARRAY_SIZE(fds_array); i++)
			{
				if(fds_array[i] < 0)
				{
					printf("accept new client[%d] and add it into array\n",connfd);
					fds_array[i] = connfd;
					found = 1;
					break;
				}
			}

			if( !found )
			{
				printf("accept new client[%d] but full,so reduse it\n",connfd);
				close(connfd);
			}
		}
		else/* data arrive from already connected client */
		{
			for(i=0; i<ARRAY_SIZE(fds_array);i++)
			{

				if( fds_array[i]<0 || !FD_ISSET(fds_array[i], &rdset))
					continue;
				if((rv =read(fds_array[i], buf, sizeof(buf)))<=0)
				{
					printf("socket[%d] read failure or get disconncet.\n",fds_array[i]);
					close(fds_array[i]);
					fds_array[i] = -1;
				}
				else
				{
					printf("socket[%d] read get %d bytes data\n",fds_array[i], rv);
					/* convert letter from lowercase to uppercase  */
					for(j=0; j<rv; j++)
						buf[j]=toupper(buf[j]);

					if( write(fds_array[i], buf, rv) < 0)
					{
						printf("socket[%d] write failure: %s\n",fds_array[i], strerror(errno));
						close(fds_array[i]);
						fds_array[i] = -1;
					}			
				}
			}
		}
	}

CleanUp:
	close(listenfd);
	return 0;
}

static inline void msleep(unsigned long ms)
{
	struct timeval			tv;

	tv.tv_sec = ms/1000;
	tv.tv_usec = (ms%1000)*1000;

	select(0, NULL, NULL, NULL, &tv);
	
}

static inline void print_usage(char *progname)
{
	printf("Usage: %s [OPTION]...\n",progname);

	printf(" %s is a socket server program,which used to verify client and echo back string from it\n ",progname);
	printf("\nMandatory arguments to long options are mandatory for short options too:\n");
	printf(" -b[daemon ] set program running on background\n");
	printf(" -p[port ] Socekt server port address\n");
	printf(" -h[help ] Display this help information\n");

	printf("\nExample； %s -b -p 8900\n", progname);
	return;
}


int socket_server_init(char *listen_ip, int listen_port)
{
	struct sockaddr_in			servaddr;
	int							rv = 0;
	int							on = 1;
	int							listenfd;

	if((listenfd = socket(AF_INET,SOCK_STREAM, 0)) < 0)
	{
		printf("Use socket() to create a TCP socket failure: %s\n",strerror(errno));
		return -1;
	}

	/* Set socket port resuseable, fix'Address already in use' bug when socket server restart */

	setsockopt(listenfd, SOL_SOCKET,SO_REUSEADDR,&on, sizeof(on));

	memset(&servaddr, 0, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(listen_port);

	if( !listen_ip )/* Listen all the local IP address */
	{
		servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	}
	else/* listen the specifid IP address */
	{
		if(inet_pton(AF_INET, listen_ip, &servaddr.sin_addr) <= 0)
		{
			printf("inet_pton() set listen IP address failure.\n");
			rv = -2;
			goto CleanUp;
		}
	}

	if(bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)))
	{
		printf("Use bind() to bind the TCP socket failure:%s\n",strerror(errno));
		rv = -3;
		goto CleanUp;
	}

	if(listen(listenfd,13) < 0)
	{
		printf("Use bind() to bind the TCP socket failure:%s\n",strerror(errno));
		rv = -4;
		goto CleanUp;
	}

CleanUp:
	if(rv<0)
		close(listenfd);
	else
		rv = listenfd;
	return rv;

}


